按PHP中的值对多维关联数组进行排序

Question

I have this set of array:

Array(
    [day_1] => Array(
        [3744] => Array(
            [time_start] => 11:00
            [time_end] => 12:00
            [notes] => 
        )
        [3746] => Array(
            [time_start] => 08:00
            [time_end] => 11:00
            [notes] => 
        )
        [532] => Array(
            [time_start] => 09:00
            [time_end] => 11:30
            [notes] => 
        )
    )
    [day_2] => Array(
        [3747] => Array(
            [time_start] => 08:00
            [time_end] => 10:00
            [notes] => 
        )
    )
)

How do I sort the array in "day_1" based on the value of "time_start"?

The end result that I want to achieve is:

Array(
    [day_1] => Array(
        [3746] => Array(
            [time_start] => 08:00
            [time_end] => 11:00
            [notes] => 
        )
        [532] => Array(
            [time_start] => 09:00
            [time_end] => 11:30
            [notes] => 
        )
        [3744] => Array(
            [time_start] => 11:00
            [time_end] => 12:00
            [notes] => 
        )
    )
    [day_2] => Array(
        [3747] => Array(
            [time_start] => 08:00
            [time_end] => 10:00
            [notes] => 
        )
    )
)

I have tried:

foreach($array['day_1'] as $key => $value){
    $starttime[$key] = strtotime($value['time_start']);
}
array_multisort($starttime, SORT_ASC, $array['day_1']);

But its not sorted and it removes my array key as well.

Answer 1

The solution using uasort function:

// $arr is your initial array
uasort($arr['day_1'], function($a, $b){
    return strcmp($a['time_start'], $b['time_start']);
});

print_r($arr);

Demo link